LA CROSSE, Wis. (AP) — Three men found slain in a western Wisconsin quarry likely knew the person or people who killed them, according to investigators.

The bodies of Peng Lor and Nemo Yang, both 24, and Trevor Maloney, 23, were discovered shortly before 5 a.m. Friday by two Milestone Quarry workers, the La Crosse County Sheriff’s Office said. The quarry is located near West Salem, about 14 miles (23 kilometers) northeast of La Crosse, which is along the Minnesota border.

La Crosse County Sheriff Jeff Wolf has called the deaths a “targeted act” but has not said how the three men died. He said he believes that they were killed Thursday night or early Friday.

The sheriff’s office on Sunday said investigators believe the men and their killer or killers were acquainted, but they didn’t specify how they might have known each other.

There is no apparent connection between the deaths and Milestone Quarry or any of their employees, Wolf said.

Sheriff’s officials are checking possible surveillance video in the area as they continue to investigate the deaths.